The Indus Waters Treaty and Hydrological Dynamics: Feasibility of Damming and Water Source Contributions

The Indus Waters Treaty and Hydrological Dynamics of the Indus, Shyok, and Jhelum Rivers: Feasibility of Damming and Water Source Contributions

Introduction

The Indus Waters Treaty (IWT), signed in 1960 between India and Pakistan with World Bank mediation, governs the allocation of the Indus River system's six rivers—Indus, Jhelum, Chenab, Ravi, Beas, and Sutlej—ensuring equitable water sharing despite geopolitical tensions. The treaty allocates the Eastern Rivers (Ravi, Beas, Sutlej) to India and the Western Rivers (Indus, Jhelum, Chenab) to Pakistan, with specific restrictions on India’s use of the latter. This note examines the IWT’s framework, the feasibility of India damming the Indus, Shyok, and Jhelum rivers to hold back water, the proportion of water from these rivers and the Chenab, Ravi, Beas, and Sutlej flowing into Pakistan, and the contributions of glacial melt versus rain-fed sources to the Indus, Shyok, and Jhelum rivers within Pakistan. By integrating legal, geopolitical, environmental, and hydrological perspectives, this analysis provides a comprehensive understanding of the Indus system’s dynamics and the implications of upstream interventions.

Structure

1. Overview of the Indus Waters Treaty
2. Feasibility of Damming the Indus, Shyok, and Jhelum Rivers
3. Water Flow Contributions to Pakistan from Chenab, Ravi, Beas, and Sutlej
4. Glacial and Rain-fed Contributions to Indus, Shyok, and Jhelum in Pakistan
5. Key Takeaways

1. Overview of the Indus Waters Treaty

The IWT is a cornerstone of India-Pakistan water cooperation, allocating the Indus system’s ~260 billion cubic meters of annual flow as follows:

• Eastern Rivers (Ravi, Beas, Sutlej): Allocated to India for unrestricted use (~41 billion cubic meters, ~33 million acre-feet, MAF). Pakistan has limited rights to use these waters before they cross the border.
• Western Rivers (Indus, Jhelum, Chenab): Allocated to Pakistan for unrestricted use (~99 billion cubic meters, ~80 MAF). India can use these for non-consumptive purposes (e.g., run-of-the-river hydropower, navigation) and limited irrigation, subject to strict design and operational constraints.
• Water Distribution: Pakistan receives 70-80% of the total flow (182-208 billion cubic meters), while India uses 20-30% (38 billion cubic meters), primarily from Eastern Rivers.
• Mechanisms: The Permanent Indus Commission facilitates communication, with disputes resolved via a three-step process (Commission, Neutral Expert, Court of Arbitration). India must share project designs and data for Western River projects.
• Resilience: Despite conflicts (e.g., 1965, 1999 wars, 2019 Pulwama attack), the IWT has endured, though India’s 2023-2024 calls for modification cite demographic growth, hydropower needs, and security concerns in Kashmir.

2. Feasibility of Damming the Indus, Shyok, and Jhelum Rivers

India’s upstream position on the Indus, Shyok, and Jhelum rivers provides theoretical leverage to dam or divert water, but the IWT, geopolitical risks, environmental constraints, and practical challenges limit feasibility. Below is an analysis for each river:

Indus River

• Context: The Indus originates in Tibet, flows through Ladakh (India), and enters Pakistan in Gilgit-Baltistan, with an annual flow of ~76-80 billion cubic meters at Besham Qila (Pakistan).
• Feasibility: India could build storage dams in Ladakh, but the IWT restricts India to non-consumptive uses (e.g., run-of-the-river hydropower) and limited irrigation. Large-scale storage would violate Pakistan’s unrestricted rights to the Indus’s flow.
• Challenges:
  • Legal: Storage dams reducing downstream flow would breach the IWT, risking arbitration, World Bank intervention, or escalation by Pakistan, which depends on the Indus for ~90% of its agriculture.
  • Geopolitical: Unilateral action could harm India’s global reputation (e.g., as G20 host in 2023) and strain ties with neighbors like Bangladesh and Nepal.
  • Environmental: High sediment loads and glacial dependence increase risks of siltation and flow reductions due to climate-driven glacier melt.
  • Practical: Damming in seismically active, remote Ladakh is costly and risks flooding Indian territory. India would still need to release most water to Pakistan, limiting utility.
• Conclusion: Damming the Indus is technically possible but legally and geopolitically unfeasible under the IWT, with high costs and limited benefits.

Shyok River

• Context: The Shyok, a major Indus tributary, originates in the Rimo Glacier (India/China border) and joins the Indus near Skardu (Pakistan), with an annual flow of ~10-12 billion cubic meters.
• Feasibility: India could dam the Shyok in Ladakh, but the IWT treats it as part of the Indus system, restricting India to non-consumptive uses. Storage dams would violate Pakistan’s rights.
• Challenges:
  • Legal: Pakistan has objected to projects like the Durbuk Shyok hydropower plant, citing flow reductions. Storage dams would face similar disputes.
  • Geopolitical: The Shyok flows through disputed Ladakh, and damming could escalate tensions with Pakistan and China (near the Line of Actual Control).
  • Environmental: Glacial sources and sediment loads pose risks, and climate change may reduce flows, limiting storage potential.
  • Practical: High-altitude construction is costly, and diverting water to other Indian rivers (e.g., Sutlej) requires complex infrastructure with limited local demand.
• Conclusion: Damming the Shyok is impractical due to IWT constraints, geopolitical risks, and environmental challenges. Run-of-the-river projects are feasible but contentious.

Jhelum River

• Context: The Jhelum originates in Kashmir (India), flows through Jammu and Kashmir, and enters Pakistan at Mangla Dam, with an annual flow of ~28-30 billion cubic meters.
• Feasibility: India has built run-of-the-river projects (e.g., Kishanganga), but storage dams to hold back water would violate the IWT, as Pakistan has unrestricted use of Jhelum’s waters.
• Challenges:
  • Legal: Pakistan has challenged projects like Kishanganga and Tulbul, citing flow impacts. Storage dams would trigger arbitration or escalation.
  • Geopolitical: The Jhelum flows through conflict-prone Kashmir, and damming could inflame tensions, especially post-2019 when India revoked Kashmir’s autonomy.
  • Environmental: Erratic snowmelt and monsoons due to climate change, plus ecosystem disruption risks, limit dam viability.
  • Practical: Storage dams would flood valuable Kashmiri land, risking local opposition, and treaty constraints limit storage capacity.
• Conclusion: Damming the Jhelum for storage is not feasible under the IWT, facing legal, geopolitical, and environmental hurdles. Run-of-the-river projects are the practical limit.

General Feasibility Notes

• IWT Restrictions: The treaty prioritizes Pakistan’s downstream rights, making storage dams on Western Rivers legally untenable without renegotiation or abrogation, both carrying high risks.
• Climate Change: Reduced glacial melt and erratic monsoons could lower river flows, reducing damming potential and increasing competition.
• Military Risks: India’s upstream advantage is tempered by the IWT’s prohibition on destroying dams and Pakistan’s potential retaliation.
• Political Will: India’s periodic threats to rethink the IWT (e.g., post-2019) are unlikely to lead to abrogation due to international backlash, though modification talks continue.

3. Water Flow Contributions to Pakistan from Chenab, Ravi, Beas, and Sutlej

The Indus system delivers ~182-208 billion cubic meters to Pakistan annually, including Western Rivers and unutilized Eastern River water. Below is the breakdown for Chenab, Ravi, Beas, and Sutlej:

• Chenab:
  • Allocation: Western River allocated to Pakistan, with India allowed non-consumptive uses.
  • Flow to Pakistan: Nearly all of the Chenab’s flow (~30-35 billion cubic meters, part of the Western Rivers’ ~99 billion cubic meters) reaches Pakistan after India’s run-of-the-river projects (e.g., Baglihar, Ratle). Pakistan has raised concerns over flow reductions, but arbitration has upheld India’s compliance.
• Ravi:
  • Allocation: Eastern River allocated to India.
  • Flow to Pakistan: India uses 95% of its Ravi allocation (8.6 billion cubic meters), but 2 MAF (2.47 billion cubic meters) flows unutilized to Pakistan, plus floodwater. Projects like Shahpurkandi Barrage (2024) and Ujh aim to reduce this flow.
• Beas:
  • Allocation: Eastern River allocated to India.
  • Flow to Pakistan: India uses nearly all its Beas allocation (~16 billion cubic meters) via projects like Pong Dam. Negligible water reaches Pakistan, except during floods.
• Sutlej:
  • Allocation: Eastern River allocated to India.
  • Flow to Pakistan: India uses 95% of its Sutlej allocation (17 billion cubic meters), with ~9.3 billion cubic meters (combined with Ravi) flowing unutilized to Pakistan, plus floodwater. India’s infrastructure minimizes this flow.
• Total Flow to Pakistan:
  • Western Rivers: ~99 billion cubic meters (nearly all to Pakistan).
  • Eastern Rivers: ~9.3 billion cubic meters unutilized (mostly Ravi, Sutlej), which India is reducing.
  • Overall: Pakistan receives ~70-80% of the Indus system’s flow.

4. Glacial and Rain-fed Contributions to Indus, Shyok, and Jhelum in Pakistan

The Indus, Shyok, and Jhelum rivers in Pakistan rely on glacial melt, snowmelt, rainfall, and baseflow from the Upper Indus Basin (UIB). Below are the contributions, based on studies (e.g., ICIMOD, Lutz et al.) and hydrological data:

Indus River

• Total Flow: ~76-80 billion cubic meters at Besham Qila.
• Glacial Flow: 30-40% (24-32 billion cubic meters), driven by Karakoram glaciers (e.g., Siachen, Baltoro). Dominant in summer (50-70% of June-September flow).
• Rain-fed Flow: 20-30% (16-24 billion cubic meters), from monsoon rains (15-25%) and westerly disturbances (5-10%). Peaks in August (30-40% of summer flow).
• Other: Snowmelt (30-35%) dominates spring; baseflow (5-10%) is minor.
• Notes: The Indus’s mixed sources make it resilient, but glacial melt is critical in dry years.

Shyok River

• Total Flow: ~10-12 billion cubic meters at the Indus confluence.
• Glacial Flow: 50-60% (5-7.2 billion cubic meters), from Karakoram glaciers (e.g., Rimo). Dominant in summer (70-80% of June-September flow).
• Rain-fed Flow: 15-25% (1.5-3 billion cubic meters), from monsoons (10-15%) and westerly disturbances (5-10%). Limited by the arid catchment.
• Other: Snowmelt (~20-25%) drives spring flows; baseflow (<5%) is negligible.
• Notes: The Shyok’s heavy glacial dependence makes it vulnerable to long-term glacier retreat.

Jhelum River

• Total Flow: ~28-30 billion cubic meters at Mangla Dam.
• Glacial Flow: 15-25% (4.2-7.5 billion cubic meters), from Himalayan glaciers (e.g., Lidder catchment). Significant in dry summers (30-40% of June-September flow).
• Rain-fed Flow: 40-50% (11.2-15 billion cubic meters), from monsoons (45%) and westerly disturbances (10%). Dominant in summer (60-70% of July-September flow).
• Other: Snowmelt (20-25%) drives spring; baseflow (5-10%) is notable in Punjab.
• Notes: The Jhelum’s monsoon reliance makes it sensitive to rainfall variability.

Hydrological Notes

• Data Variability: Estimates vary due to gauge locations, study methodologies, and climate-driven changes. Glacial and snowmelt contributions are often combined in older studies.
• Climate Change: Accelerated glacial melt may temporarily increase flows, but long-term glacier retreat could reduce contributions, especially for the Shyok. Monsoon variability affects the Jhelum most.
• Local Inputs: The Indus and Jhelum gain rain-fed tributaries in Pakistan (e.g., Hunza, Kunhar), boosting rainfall shares downstream. The Shyok’s arid catchment limits local inputs.

5. Key Takeaways

1. IWT as a Binding Framework: The IWT allocates the Indus, Shyok, and Jhelum to Pakistan, restricting India to non-consumptive uses. Storage dams to hold back water would violate the treaty, risking legal disputes, arbitration, or escalation, making them unfeasible without abrogation, which carries severe geopolitical costs.
2. Limited Damming Feasibility: Technical feasibility exists for damming the Indus, Shyok, and Jhelum, but legal (IWT violations), geopolitical (tensions with Pakistan/China), environmental (sediment, climate change), and practical (cost, flooding) constraints render storage dams impractical. Run-of-the-river hydropower is the viable limit, though contentious.
3. Pakistan’s Water Dependence: Pakistan receives 70-80% of the Indus system’s flow (182-208 billion cubic meters), including nearly all Chenab, Indus, and Jhelum waters (99 billion cubic meters) and ~9.3 billion cubic meters of unutilized Ravi/Sutlej water. India is reducing Eastern River flows via projects like Shahpurkandi, but Western Rivers remain critical for Pakistan’s agriculture (90% of food production).
4. Hydrological Diversity:
   • Indus: Mixed sources (30-40% glacial, 20-30% rain-fed, 30-50% snowmelt/baseflow), with glacial melt critical in summer. Resilient but sensitive to glacier retreat.
   • Shyok: Glacier-dominated (50-60% glacial, 15-25% rain-fed), vulnerable to long-term glacial decline due to minimal rainfall.
   • Jhelum: Monsoon-driven (40-50% rain-fed, 15-25% glacial), sensitive to rainfall variability but less reliant on glaciers.
5. Climate Change Risks: Glacial melt (critical for Shyok, significant for Indus) may decline long-term, reducing flows, while erratic monsoons threaten Jhelum’s reliability. These trends exacerbate competition and complicate damming plans.
6. Cooperation Potential: Proposals for India to use unutilized Ravi/Sutlej water via Pakistan’s infrastructure (e.g., Sukkur Barrage) exist but are hindered by distrust. The IWT’s dispute resolution mechanisms remain vital for managing tensions over projects like Kishanganga or Baglihar.

Conclusion

The Indus Waters Treaty ensures Pakistan’s access to the Indus, Shyok, and Jhelum rivers, making large-scale damming by India legally and geopolitically unfeasible, despite technical possibilities. Pakistan receives the majority of the Indus system’s flow, with the Chenab, Indus, and Jhelum delivering nearly all their waters, while India optimizes Eastern River use. Hydrologically, the Indus is balanced between glacial and rain-fed sources, the Shyok is glacier-dominated, and the Jhelum is monsoon-driven, with climate change posing long-term risks to all. The IWT’s resilience, combined with careful management of run-of-the-river projects and climate adaptation, is critical for sustaining this vital water-sharing framework amidst growing pressures.